Any idea why my USB ports will not see any thumb drives? 2012 Yellow Jacket with 730N RHR radio. Neither the port on the front of the radio or the 1 in the console will see a drive. When I insert a cable to my cell phone, the phones starts charging, so I know the port is supplying power and I see the LED on a thumb drive come when inserted, but when I go into upload files, is shows an Icon for Disc and 1 for USB, but the USB is dimmed out so it cannot be used. Any thoughts before I take it in??